EDM apparatuses utilizing a moving wire electrode are commonly presently used in making precise cuts and shaping various electrically conductive materials or workpieces. Typically, the wire electrode is wound around and travels between two turning spools and a pair of wire guides or guide assemblies wherethrough the wire travels are used to accurately situate or guide the moving wire electrode at the proper location and at an angle with respect to the workpiece being cut. The wire and workpiece are placed at different electrical potentials and a controlled electrical spark traveling between the wire and workpiece causes the workpiece to be eroded and cut or shaped in a desired configuration.
The older wire guides, as for example, is disclosed in Hague et al., U.S. Pat. No. 4,250,371 utilizes groove guides for positioning the wire electrode with respect to the workpiece. A disadvantage with the groove guides is that they are, in essence, unidirectional.
Other wire electrode guides utilize a hole or bore slightly larger in diameter than the wire electrode for guiding the wire and are, thus, multidirectional. Examples of these are shown in U.S. Pat. Nos. 4,539,459, 4,559,433, 4,250,371, and also in Japanese application Nos. 59-102253, 59-195654, 59-237616, 59-93256, 53-143932, 54-33574, 54-56005, 54-56591, 54-58930, 54-150893, 54-157314, 54-162051, 55-3910. However, the prior multidirectional wire guides have substantial shortcomings and drawbacks. For example, the final or post guide members are part of an overall guide assembly and depend on other components for the accurate placement of the guide member bores. Further, as the guide members wear, the entire guide assembly generally must be disassembled and the whole post guide or pre guide body housing the guide members must be replaced. Further yet, vibrations placed on the wire by the various current pickup assemblies is carried through the post or final guide and causes inaccuracies in the cutting of the workpiece. Accordingly, a need exists for a guide assembly that solves the problems associated with prior guides and guide assemblies while decreasing manufacturing costs and providing for easier replacement of the various guide members.